The following abbreviations are utilized herein:
3GPP third generation partnership project
AAA access, authorization and accounting (server)
ACK acknowledgement
ADC analog to digital converter/conversion
AGC automatic gain control
aGW access gateway
AN access node
ARQ automatic repeat-request
ASIC application specific integrated circuit
AT allocation table
ATM asynchronous transfer mode
BS base station
CDMA code division multiple access
CRC cyclic redundancy check
DAC digital to analog converter/conversion
DL downlink (Node B to UE)
DRX discontinuous reception
DSP digital signal processor
DTX discontinuous transmission
eNB E-UTRAN Node B (evolved/enhanced Node B)
EPROM erasable programmable read-only memory
E-UTRAN evolved universal terrestrial radio access network
FDMA frequency division multiple access
FEC forward error correction
FPGA field programmable gate array
GGSN gateway GPRS support node
GPRS general packet radio service
HARQ hybrid automatic repeat-request
IEEE institute of electrical and electronics engineers
IP internet protocol
IR infrared
LDPC low density parity check
LTE long term evolution of UTRAN (E-UTRAN)
MAC medium access control (layer 2, L2)
MCS modulation and coding scheme
MM mobility management
MME mobile management entity
MS mobile station
NACK negative acknowledgement
Node B base station
OFDMA orthogonal frequency division multiple access
PCMCIA personal computer memory card international association
PDCCH physical downlink control channel
PDCP packet data convergence protocol
PDSCCH physical downlink shared control channel
PHY physical layer (layer 1, L1)
PROM programmable read-only memory
PSTN public switched telephone network
RAM random access memory
RB radio bearer
Re-TX retransmission
RF radio frequency
RLC radio link control
ROM read-only memory
RRC radio resource control
RRM radio resource management
RX reception
SAE system architecture evolution of UTRAN
SAW stop-and-wait
SC-FDMA single carrier-frequency division multiple access
SFN system frame number
SGSN serving GPRS support node
SIB system information block
SIM subscriber identity module
TDMA time division multiple access
TX transmission
UE user equipment, such as a mobile station or mobile terminal
UL uplink (UE to Node B)
UPE user plane entity
UTRAN universal terrestrial radio access network
VoIP voice over internet protocol
WCDMA wideband code division multiple access
WiMAX worldwide interoperability for microwave access (IEEE 802.16 standard)
WLAN wireless local area network
Radio communication systems, such as wireless data networks (e.g., 3GPP LTE systems, spread spectrum systems (e.g., CDMA networks), TDMA networks, WiMAX, etc.), provide users with the convenience of mobility along with a rich set of services and features. This convenience has spawned significant adoption by an ever growing number of consumers as an accepted mode of communication for business and personal use. To promote greater adoption, the telecommunication industry, from manufacturers to service providers, has agreed to develop standards for communication protocols that underlie the various services and features. One area of effort involves resource scheduling, for example, to correct transmission errors and ensure accurate delivery of data.
There are various error control mechanisms that can be utilized by wireless communication systems. These mechanisms may be useful in detecting the presence of errors (e.g., incomplete or corrupt receptions) and in addressing errors (e.g., retransmission of messages and/or data).
As a non-limiting example, one such error control mechanism is HARQ. HARQ is a variation of the ARQ error control. With ARQ, error-detection information (ED) bits are added to data to be transmitted (e.g., a CRC). With HARQ, FEC bits are also added to the existing ED bits (e.g., a Reed-Solomon code, a Turbo code, a LDPC code). Various types of HARQ may involve the transmission of the ED bits and/or the FEC bits, possibly over multiple transmissions. The ED bits and the FEC bits enable a receiver to determine if there are errors with received transmissions. If a transmission is incorrectly received, the receiver may indicate this to the transmitter (e.g., via a NACK) and request retransmission of the incorrectly-received message. Upon receipt of the indication and/or request, the transmitter can retransmit the same message or another message containing the same data and/or information. If a transmission is correctly received, a receiver may indicate this to the transmitter (e.g., via an ACK) and there may be no need for retransmission.
As a result of HARQ using the additional FEC bits, in poor signal conditions HARQ tends to perform better (e.g., with better accuracy) than ordinary ARQ. In some cases, the improved performance of HARQ may come at the expense of lower throughput, even in good signal conditions (e.g., Type I HARQ). In other cases, HARQ may be used without further adversely affecting throughput in comparison with ordinary ARQ (e.g., Type II HARQ).